Copper is commonly utilized in structures of integrated circuit (IC) chips. For instance, copper lines may be utilized for wiring; and copper pads may be utilized as bond pad regions associated with an IC chip for connection to circuitry external of the chip.
Copper is readily oxidized upon exposure to air. Accordingly, protective materials are frequently provided over the copper utilized in IC chips. Such protective materials may be a combination of nickel and gold, or a combination of nickel and palladium. Specifically, nickel may be electroless plated directly on the copper, and subsequently gold or palladium may be formed directly over the nickel.
The copper and protective materials thereover will frequently be surrounded by insulative material (such as silicon dioxide). A problem may occur with the insulative material poorly adhering to the protective materials so that cracks develop between the protective materials and the insulative material. Such cracks may permit oxidants (such as O2 or water vapor) to reach the copper. The oxidants may then oxidize the copper and create defects which propagate through the copper and impair performance of an IC chip.